Heliatek GmbH, a global company in the production of organic solar film, has reached a new record in the efficiency of transparent solar cells. The latest development allows transparency levels up to 40% with an efficiency of over 7%. The company already holds the world record of 12% cell efficiency for opaque (non-transparent) organic solar cells.
This lab development underscores the company’s strategy to supply its transparent HeliaFilm™ to glass manufacturers for both building integration (BIPV) and car roofs.
|The HeliaFilm transparent film (Source: Heliatek)
“The transparency of our products is at the core of our market approach. The HeliaFilm™ is customized to meet our partners’ specific needs,” said Thibaud Le Séguillon, CEO of Heliatek. “We supply components, and this component is a film which combines transparency and energy generation. This unique combination widens our market potential.”
Both these application areas use tinted glass to reduce glare which can be done by applying a film, so changing the film to one that generates electricity as well is a drop-in for manufacturers. Using HeliaFilm™ in glass car roofs will not only generate energy, but will also allow the car manufacturers to claim Eco-innovation credits towards CO2 emission goals. Architectural glass panels and windows incorporating HeliaFilm™ enable electricity to be discretely generated on the outside envelope of a building.
Importantly for these applications, Heliatek’s technology continues to be effective at generating electricity at low light levels, any orientation and at high temperatures, which are conditions where conventional solar lose efficiency.
The latest generation of organic solar cells with a 40% light transparency reaches an efficiency record of 7.2%. The measurement follows standard testing conditions using a white background. Heliatek thus succeeded in generating an optimal energy conversion for transparent HeliaFilm™. Currently, 12% efficiency is being reached with opaque cells. The 7.2% mirror the same efficiency, since the partial transparency allows the usage of only 60% of the light for the energy harvesting. Depending on the application, the balance between light let through and electricity generated can be adjusted.
The production of HeliaFilm™ is based on small molecules (oligomers), which are being developed and synthesized at Heliatek. Oligomers are being deposited at low temperatures in a roll-to-roll vacuum process. One unique feature of the molecules used is their selective absorption of the solar spectrum, which allows different colors and transparency. The photoactive materials selectively convert sun light into electricity. The production of transparent HeliaFilm™ is possible with the introduction of transparent conductive layers at the front- and back-side of the solar cells.